Liquid cooling of high temperature bodies



Nov. 14, 1944. c. v. LITTON LIQUID COOLING OF HIGH TEMPERATURE BODIES Filed Oct. 5, 1942 3 Sheets-Sheet 1 ATTOIBAI'EYI Nov. 14, 1944. c. v. LITTON LIQUID COOLING OF HIGH TEMPERATURE BODIES 3 Sheets-Sheet 2 Filed Oct. 5, 1942 FIGS.

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INVENTORY flan/945s 1! 1/770 Nov.- 14, 1944. .c; v. LITTON- LI'QUID COOLING OF HIGH TEMPERATURE BODIES Filed Oct. 5, 1942 3 Sheets$heet 3 F IGM.

FIGS.

uvmvrox. 62942458 V0770 ATTORNEY Patented Nov, 14, 1944 UNITED ,STATE.

Charles v. Litton, I to International New York, N. Y., a co LIQUID COOLING OF HIGH TEMPERATURE 4 I BODIES 7 Redwood City, Calif., assignor Standard'Electric Corporation,

rporation of Delaware Application flctober 5, 1942, Serial No. 460,800

15 Claims. (01. 2s0-27.5)

. This invention relatesto liquid cooling of high temperature body withspecific relation to the cooling of vacuum tube anodes.

This invention is a continuation-in-part of mycopending applications Ser. No. 429,811, filed February '7, 1942, and Ser. No. 446,034, filed June 6, 1942.

In theart of cooling hotbodies by a liquid in either direct'orindirect contact therewith, the

fact that the temperature of the body in contact with the cooling liquid shouldnot be higher than the boilingpoint of the cooling, liquid seems either to have been, in many cases, entirely disregarded, or ifthis 'fact'has been recognized, the workers in the art have turned to other cooling media, such as air. Obviously, if thetemperature of thehot body in Contact with the liquid cooling medium is ,above the boiling. point of that medium, there will not beliquid contact along the surface of the .hot body, but rather a contact, for example, of vapor or vapor bubbles. This immediatelydisrupts the cooling 'eifect of the liquid and in a sense, one might-say that liquid cooling is no longer present.

It is the primary object of the present invention to provide proper and efiicient cooling of 'hot bodies by means oiliquid, retaining all'oi the advantages o'fliquid cooling while eliminating obvious disadvantages and still efiicientlycooling hot bodies whose radiant surface temperature is above the boiling point of the cooling liquid.

The above mentioned and further objects-and advantages of my invention and the manner of attaining .them will be more fully .explainedin the following description taken in' conjunction with the accompanying drawings. In the draws ,Fig. 1 is a vertical cross-sectional view illustrating a finned liquid-cooled anode with a cooling arrangement formed in accordance with the basic principles ofthe present invention;

sectional view taken arrangement illustrated in Fig. 5; I

Fig. 7 is a vertical, broken, cross-sectional view of a still further modified arrangement for the coolingof a vacuum-tube anode; 3 v

Fig. 8 is apartial enlargedhorizontal crosssectional view of the arrangement illustrated in Fig. 2 is a partial horizontalcross-sectional I view taken along the line 2-2 of Fig. 1 and drawn to a larger scale, showing the arrangement of fins in accordance with the presentinvention;

Fig. 3 is a vertical cross-sectional view ofaa modified formof cooling means-for a vacuum tube 1 anode; g V

Fig. .4 is a :partial horizontal cross-sectional view taken along'the line 44 of Fig. 3 and drawn toaIargerscaIe;

5 is a vertical, cross-sectional view of a vacuum tube anode cooled in accordance with a still further arrangement;

a partial enlarged horizontal cross- Fig. 9 is a vertical, broken, cross-sectional view of a cooling arrangement for avacuum tu-beanode, involving 'both longitudinal and annular cooling fins;

Fig. 10 is a partial enlargedhorizontal orosssectional view taken along the line Ill- 10 of the arrangement illustrated in Fig. 9;

Fig. llis a vertical, broken, cross-sectional view of an additional modified cooling arrangement for vacuum tube anodes; and

Fig. '12 is any enlarged, partial, horizontal crosssectionalview taken. along the line of IZ-IZ of the arrangement illustrated in Fig, 11.

.A cooling system in its simplest form .is illustrated in Figs. 1 and 2, showing an arrangement,

for cooling the anode l0 forming .part of the envelope of a vacuum tube H. In the case of such a tube, itmay be necessary to dissipate aheat of 2000 watts per square inch of anode surface, and it will be assumed, for purposes of explanation,

that the highest temperature, at which the tube can be operated without injury, is with an anode surface temperature'of 320 C. The maximum water temperature, however, for efiicient cooling purposes would be C representing a temperature diflerence of 220 C. If anode 'lll is surroundedby a tubularmember 12 having attached to its inner surface a plurality vof longi'tudinal circumferentially spaced, fins l3 extending inwardly to contact the surface of the anode, the temperature oi the anode will tend to drive the heat outwardly along thesefins toward tubular member l2. By choosing fins of proper width the circumferential areaabout their outer edges may be so increased that the resultant heat to be dissipated from the effective radiatingsurface (pre- 45.

viously taken as ZOOOWatts per square inch at the surface of the anode) will bei'red'ucedto500 watts per square inch, equivalentto'a temperature of 100 C. The fins may then-be cooledby means of a suitable water jacket-formed of a casing I4 enclosing tubular member 12 but'in spaced relation thereto, the water jacket having an inlet l5 andan outlet 16. With-this arrangement, in no case will the cooling water i come in contact with metal above 100 (3.; and thus the water cooling will be wholly efficient. The temperature graalong the line 6 6 of the dient of 220 between the anode surface and the metal in contact with the coolin water will insure that the heat is conducted outwardly from the anode surface to the cooling jacket. It is to be noted, in this connection, that if a finned anode were merely plunged into water, such temperature gradient would not exist,'and the heat would not be driven outwardly. structurally speaking, the arrangement in Figs. 1 and 2 is quite similar to that shown in my co-pending application Ser. No. 429,871,

Another embodiment of the invention is shown diagrammatically in Figs. 3 and 4. Anode of tube 3! is shown enclosed in a cooling arrangement comprising fins 33 engaging the surface of the anode. circled by one or more coils of tubing for a cooling fiuid. A single coil 34 is shown in the drawings having an inlet 35 and an outlet 36 The helical cooling coil is utilized in somewhat the N same manner as shown in my co-pending application 446,034.

To assist in the cooling action, I havealso provided in this form of invention a suitable annular header 31 which is adapted to throw a fine spray downwardly along the fins 33 through suitable nozzles or openings 38. By using this arrangement the temperature at the outer edges of fins 33, in contact with the cooling tube 34 may be less than 100 C., so that one cooling tube will suifice. The use of the spray over the fins 33 merely permits that advantage be taken of the latent heat of evaporation of the water falling over the hot fins. The main cooling, however, is

- still done by the liquid in tube 34, and the basic principles of the present invention, namely, utilizing the temperature gradient through the fins to drive the heat outwardly and to limit the temperature of the fins in contact with the cooling medium to 100 C., or less, is still maintained.

Another embodiment of the invention is illustrated in Figs. 5 and 6 in which anode of tube 5! is shown diagrammatically in a, cooling arrangement including a plurality of fins 52. The

fins and associated equipment in this embodiment as well as the others in the present application will be understood to be assembled and supported by any suitable arrangement, the details of which will be understood by those skilled in the art.

In the form of invention shown in Figs. 5 and 6, the longitudinal fins 52 have been widened, as compared to the type of construction illustrated in Figs. 1 to 4, inclusive, to such an extent that the heat to be dissipated at the outer edges of these fins will be in the Vicinity of C. The fins are then cooled by a plurality of sets of vertical tubes 58, 51, 58. The inlet tubes 56 are preferably connected together at one end by suitable means, such as the inlet header 59. The cooling water then flows upwardly through these tubes, is returned through the individual return tubes 51, whence it again flows upward through the tubes 58 to provide further cooling of the fins. The ends of tubes 58 may be connected together in an outlet header 69, from which the water is then drawn away. If the arrangement is properly d signed, the temperature of the fins in the vicinity of the inlet tubes 56, will be approximately 65 C., and the water flowing through the tubes 56 will reach this temperature at the end of the tubes. This temperature will be maintained in the tube 51, but in the outlet tube 58, adjacent which the fin temperature is approximately 100 0., the water will be still further heated and will leave the outlet header at a temperature preferably j The outer edges of the fins are en- 1 below its boiling point. .It will again be seen that in the form of invention illustrated in Figs. 5 and 6 the principle of providing a temperature gradient throughout the length of the fins 52 has been retained, while, again, the temperature of the fins in contact with the cooling liquid is never above the boiling point of the cooling liquid.

Figs. '7 and 8 show another form of the invention in which anode 10 of tube 1| is enclosed in a cooling arrangement in which a plurality of longitudinal fins 12 project from the inner surface of a casing 14 and contact the anode 19. On the outside of casing 14 is a second set of fins 15. These fins, for maximum efiiciency should be of triangular cross-section as shown in Figure 8. Each fin is slotted, and in the present embodiment, three sets of cooling pipes, 16, 11 and 18 are disposed in each slot. The corresponding pipes in each fin are connected to common headers, pipes 16 being connected between headers 89 and 8|; 11 between headers 82 and 83 and the innermost pipes 18 are connected between headers 84 and 85. Beyond the edges of the fins 15, the lower header for the outer row of pipes is connected to the upper header 83 for the middle row or pipes 11 by a series of small pipes 86.

-Likewise, lower header 82 for the middle row of pipes is connected by pipes 81 to the upper header 85 for innermost pipes 18. An inlet for cooling fluid is shown at 88 connected to header 8| and an outlet 89 is shown connected to header 84. Instead of numerous small pipes 86 and 81 interconnecting the headers, single pipes of sufiicient capacity could be used, provided the proper direction of flow of the cooling liquid is maintained, which is indicated by arrows in the drawings.

Fins 15 are proportioned preferably '50 that the change in cross-section through which the heat is transmitted is closely proportional to the amount of heat to be transmitted, so that the temperature of the fins drops off linearly outwardly. The direction of the flow of the cooling fluid is the same in tubes 15, 11 and 18, tube 16 being the coolest, while 18 is the hottest.

Construction of the arrangement just described would be simplified if fins 15 were of rectangular instead of triangular cross-section. Some loss in eiiiciency would result, but if the fins were properly proportioned, effective cooling could be accomplished. Preferably, in this case, the thickness of the fins should be about two thirds of their width.

Still another-form of the invention is illustrated in Figs. 9 and 10 which show the anode 99 of a tube 9| disposed within a cooling apparatus comprising a casing 92 from the inner surface of which fins 93 project and contact anode 90, On the outside of casing 92 a plurality of helical fins 94 are formed or attached by any suitable method. Fins 94 may be of oblong cross section as shown in Fig. 9 or they may be of a slotted triangular cross-section as shown in Fig. 8. The embodiment as shown in Fig. 9 contemplates twelve or fifteen fins, though any suitable number may be used, between which are disposed an under layer of cooling tubes 95 and an upper layer 96. A header 91 to which the upper ends of tubes 96 are connected individually in spaced circumferential relation is provided with an inlet pipe 98. The lower ends of the tubes in this layer are similarly connected to a header 99 which in turn is connected for example, by a pipe I00 to header I III at the upper part of the cooling device. Tubes 95 of the lower layer are connected in the manner described between header HH and a. lower header than that at which, water normally boils.

ata-tir- 3- arrangement which produces a temperature gradientin outer fins 94.

' v e arrangement shown in Figs. 9 and pro vides a way by which small tubes may beused to effectively conduct a large volume of'cooling; fluid st that the desired number'of gallons pers'niinute 10 may be forced through the tubes.

Vilhile the above embodiments of the invention ave been; generally described as using water for cooling a-heated body whichhas a temperature insufficient to cause the cooling fluid to boil and 5 thus loseits eflici'ency, it will be apparent that the various cooling systems of the invention, particularly those shown in Figs. 3 to 10 will operate successfully at temperatures considerably higher is because the resistance to the formation of steam'bubbles is greater in applicants structure than in the well-known water jacket. Steam bubbles, in order to form, must displace an equal volume of water. jacket this merely pushes the water around to the other side of the anode. In the present invention, in order for steam to form, each bubble must give a large velocity increase to a long column of water flowing through a small tube with considerable friction, consequently, a temv perature considerably above boiling point is required to overcome the effective pressure of the water in the tubes before steam bubbles will form.

In Figs. ll and-12 another modification of the invention is illustrated adapted for cooling with I a liquid such as Prestone in place of water .permitting a higher liquid contact temperature. The anode H0 of tube III is enclosed in a relative thick sleeve H2 of a suitable heat conduct- 4o ing metal contacting with its inner surface anode I I0 and having formed on or secured to its outer surface a single helical fin I I3. Between the convolutions of the fin are, for example three layers oftubing H4, H5, H6 for the cooling fluid. The 4.5

fluidis fed in through inlet H1 at the bottom 5 of the outer layer H6 of tubes, and is led by an external pipe H8 to the lower part of the middle layer H5 and from the top of the middle layer by external pipe H9 to the bottom terminaliof inner layer H4, the top part of which isconnected to output pipe I20. The metal sleeve l l2 in this case provides. the necessary heat gradient between the surface of the anode and the spirally positioned cooling fins.

The embodiment shown in Figs. 11 and 12 may be modified so as to carry a greater volume of cooling fiuidby using a parallel spiral tube arrangement as shown in Fig. 9 but with a cooling fluid such as Prestone fewer pipes inparallel would be required. 7 p 7 Other modifications of the invention will occur to those skilled in the art without departing from the spirit of the invention as described in the following claims. .65

1 What is claimed is:

1. -An arrangement for cooling a hot body by a liquid, which comprises a plurality'of fins dis posed around said body having a temperature gradient thereacross, means' for increasing the'70 temperature gradient for said fins which comprises means for spraying water thereon in such volume that the water is immediately converted into steam, and further cooling means for said fins comprising tube means disposed about the This 20 In the conventional water 5 edgesthereof remote 1 from said body through w-hicliacooling liquid flows;

A {cooling arrangement for electron tubes an the like comprising a plurality of heat conducting ,fins disposed to conduct heat from the surface of thetube to be cooled, a plurality of rows of pipes for a cooling liquid disposed between the respective fins near the edges thereof remote from said tube, said fins being so propor- 3; A cooling arrangement according to claim 2 in which said conduit means are arranged to interconnect the respective rows of pipes so that the cooling fluid of all rows flows in the same direction.

' 4. A cooling arrangement according to claim 2 in which two pipes are provided between the re.- spective fins, one pipe being connected to the other by aconduit beyond said fins and in which the outer pipes are all connected to a common header fromwhich cooling fluid flows, and the inner pipes to a common outlet header.

5. A cooling arrangement for electron tubes and the like comprising a casing adapted to substantially enclose the part of the tube to be cooled,

a plurality of heat conducting fins extending from the inner surface of said casing to-the surface of the tube, a plurality of rows of fins on the outer surface of said casing, a plurality of layers of pipes between the last mentionedfins through "which a cooling fluid flows, a common header for opposite terminals of the pipes in the respective rows, and conduit means for interconnecting the respective layers of pipes so that a heat client is maintained across each of the last mentioned fins.

6. A cooling arrangement according to claim 5 which the fins on the outer surface of said casing having a triangular cross-sectiomeach fin being slotted, said layers of pipes being disposed in the slots.

7. A cooling arrangement according to claim 5 in which the cooling fins on the outside of said casing are formed in a spiral with a plurality of layers of spiral cooling pipes disposed therebetween.

8. A cooling arrangement for electron tubes and-the-like comprising a sleeve surroundingthe 5 tube to be cooled, said sleeve being of suflicient thickness to cause a desired temperature gradient between the tube and outer surface of the sleeve, a plurality of fins arranged to cool the outer surface of said sleeve, a plurality of layers of pipes for a cooling fluid in contact with said fins and means to interconnect the respective layers of pipe to a source of cooling fluid so thata temperature gradient is maintained in said fins.

-9. A heat conducting support for an electron tube comprising a heat conducting sleeve construction including a plurality of fins atleast partly separated from one another fitting the anode end of the tube, said fins extending radially outwardly to an outer surface of sufiicient area to maintain a temperature below the boiling point of water, and a water cooling system associated with said outer surface comprising a plurality of adjacent runs of heat conducting water pipe interconnected to form a continuous water circulating system.

10. A heat conducting support as set forth in claim 9, in which the water pipeis arranged as a continuous helix in contact with said surface.

11. A heat conducting support as set forth in claim 9, in which said outer surface is provided With a helical fin, and the water pipe is in the form of a continuous helix located between runs of said fin.

12. A heat conducting support for an electron tube comprising a heat conducting sleeve construction fitting the anode end of the tub and extending radially outwardly to an outer surface of sufiicient area to maintain a temperature below the boiling point of water, and a Water-cooling system associated with said outer surface comprising a plurality of superposed cooling units, each unit including a plurality of adjacent runs of heat conducting Water pipe interconnected to form a continuous water circulating system, said units being connected in series and provided with a water inlet in the outer unit and a water outlet 13. A heat conducting support as set forth in claim 12, in which each unit includa a header at each end.

14. Aheat conducting support as set forth in claim 12, in which each unit comprises helically arranged pipe runs extending around said outer surface.

' 15. A heat conducting support as set forth in claim 12, in which said outer surface includes a helical fin and each unit includes a helical pipe located between runs of said fin.

CHARLES V. LITTON. 

